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Schoch R.R.,Staatliches Museum fur Naturkunde Stuttgart
Journal of Systematic Palaeontology | Year: 2013

Phylogenetic analysis of a large dataset (72 taxa, 212 characters) focuses on the in-group relationships of temnospondyls, the largest lower tetrapod clade. Representatives of all clades and grades were considered, spanning the entire stratigraphical range of temnospondyls from the Early Carboniferous through to the Early Cretaceous. Several major groups are defined phylogenetically (node or branch-based) rather than by apomorphies. The following groups were unequivocally found to be monophyletic: Edopoidea (node), Dvinosauria (stem, excl. Brachyopidae), Dissorophoidea (node), Eryopidae (stem), and Stereospondyli (node). The latter encompass three well-defined, branch-based taxa: Rhinesuchidae, Trematosauria and Capitosauria. Trematosauria (stem) contain Trematosauroidea (node), which includes the classic trematosaurids, metoposaurids, and possibly part of the rhytidosteids (Peltostega) but their in-group relationships remain unsettled; most other short-snouted stereospondyls (chigutisaurids, brachyopids, Laidleria and the plagiosaurids) are probably monophyletic and likely nest in some form with trematosauroids. Capitosauria (stem) include the Capitosauroidea (node) spanned by Parotosuchus and Mastodonsaurus, with the successive stem taxa Edingerella, Benthosuchus, Wetlugasaurus and Watsonisuchus. In all variant analyses, edopoids form the basalmost temnospondyl clade, followed by a potential clade (or grade) of small terrestrial taxa containing Balanerpeton and Dendrerpeton (Dendrerpetontidae). All taxa higher than Edopoidea are suggested to form the monophyletic stem taxon Eutemnospondyli, tax. nov. The remainder of Temnospondyli fall into four robust and undisputed clades: (1) Dvinosauria; (2) Zatracheidae plus Dissorophoidea; (3) Eryopidae; and (4) Stereospondyli. These taxa are together referred to as Rhachitomi (node). Eryopidae and Stereospondylomorpha are probably monophyletic, here referred to as Eryopiformes (tax. nov.). The position of Dissorophoidea + Zatracheidae is still ambiguous; it may either form the sister taxon of Dvinosauria, or nest between Dvinosauria and Eryopiformes, whereas there is no support for Euskelia (Dissorophoidea + Eryopidae) after basal taxa of each clade are better understood. © 2013 Copyright Taylor and Francis Group, LLC.

Richling I.,Staatliches Museum fur Naturkunde Stuttgart | Bouchet P.,French Natural History Museum
Biodiversity and Conservation | Year: 2013

Recent literature abounds with reports of the decline and extinction of the endemic species of Achatinellidae and Partulidae in the Hawaiian and Society Islands, respectively, resulting from the introduction of the predatory snail Euglandina rosea. Here, we describe a previously unrecognised radiation of helicinid land snails from the Gambier Islands of French Polynesia, with up to seven species co-occurring in a single locality and up to eight species on a single island. This radiation had already become extinct (nine of ten species) several decades before the expansion of E. rosea in the Pacific, and even before the species were collected for scientific study. The Gambier Islands case study shows that massive extinctions of endemic land snails had already taken place in the nineteenth century, but have remained largely unrecognised and undocumented. Nine of the ten species are new to science and are described here almost entirely based on empty shells collected from the shell bank of the soil after the extinction had already taken place. This helicinid radiation alone increases the number of documented global mollusc extinctions by almost 2 %. Most of the species are minute and, at 1.5 mm, rank among the smallest, if not the smallest, species in the family. Several have apertural barriers and one has opercular apophyses-character states not previously documented in Pacific helicinids. Whereas the only surviving Gambier species belongs anatomically to the genus Sturanya, representative helicinid species from the Austral, Society and Cook Islands are not congeneric with it, and the generic name Nesiocina is here established for the latter taxa. It is hypothesised that the extinct Gambier species were also Nesiocina. © 2013 Springer Science+Business Media Dordrecht.

Rasser M.W.,Staatliches Museum fur Naturkunde Stuttgart
Hydrobiologia | Year: 2014

The Miocene Steinheim Basin in SW Germany is an ancient (long-lived) palaeo-lake that has existed over some hundreds of thousands of years. It is an iconic fossil site, because the historically oldest phylogenetic tree of extinct organisms was based on specimens described from this locality. Today the basin contains 30–40 m thickness of lake sediments with planorbid snails of the genus Gyraulus occurring in rock-forming quantities. The shells are morphologically highly disparate with forms ranging from the tiny, planispiral founder species Gyraulus kleini, to fragile corkscrew-like uncoiled forms and to large trochiform morphs with thick shells. In total, this presumably monophyletic species flock contains 17 species distributed in time and space, all of which are endemic, except for the founder species. Up to nine of them occur in a single sedimentary level and are inferred to have lived together. Such an extreme rate of endemism makes fossil Lake Steinheim special among extant and fossil lakes. This review article summarises and discusses the species concept(s), indications for endemism, speciation processes, the phylogenetic concept(s) and factors controlling evolution. It also provides directions for future research. © 2013, Springer Science+Business Media Dordrecht.

Rasser M.W.,Staatliches Museum fur Naturkunde Stuttgart
Zoosystematics and Evolution | Year: 2013

Among others, "Darwin's dilemma" is referred to as Charles Darwin's perception that his theory on the origin of species suffers from a scarcity of fossil evidence such as transitional forms between taxa. In 1867, only afew years after the publication of Darwin's "Origin of Species", Franz Hilgendorf published a phylogenetic tree of Miocene planorbid snails from the Steinheim meteorite crater lake in SW Germany. This tree was widely ignoredby Darwin, although it would have been a perfect solution for his "dilemma". Surprisingly, the reason for his ignorance was the influence of contemporary German and US palaeontologists, who had been followers of the "anti-Darwinian" orthogenesis concept, which implies the consistency of species and the refusal of the idea that one species may branch into two new species. During the last decades, several studies have supported the appropriateness of Hilgendorf's concept, whom S. J. Gould called one of the first "Darwinians". With good reason his tree of planorbid snails is seen today as the first phylogenetic tree of fossils and one of the first fossil evidences for Darwin's descendent-theory. ©2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Schoch R.R.,Staatliches Museum fur Naturkunde Stuttgart
Neues Jahrbuch fur Geologie und Palaontologie - Abhandlungen | Year: 2011

A new find of a tetrapod mandible with unique teeth is reported from the Middle Triassic Lower Keuper. The outline of the dentary, morphology of the teeth and their emplacement suggest that the remain represents a new procolophonid parareptile. The abbreviated dentary, the high coronoid process, and the shape of the teeth resemble those of leptopleuronines. Unique features are the crown morphology, marked parallel striations, the possession of two similar, very large durophagous teeth, the edentulous anterior portion, and the lack of a coronoid suture. Thus, although the jaw resembles procolophonids in some features, it is argued that referral to this group needs recognition of more clearly established character-states, prompting the search for more complete material in the same deposits. © 2011 E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Germany.

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